A monthly gathering of people to ride bikes around a city or town. Its general purpose is to raise awareness that people ride bikes for transportation too and roads should be more accomidating for bikes. With many cyclists riding together in a group they are able to reach a "critical mass" and become a powerful entity of the roads, taking up many lanes.

Invented in San Francisco, it is celebrated in many cities across the world due to its simplicity to organize, often all you need to is spread the word about it. In San Francisco and New York participants often number in the thousands. It is usually at the end of the day on the last Friday of every month, at a standard, well-known gathering spot.

Often criticized by motorists as a nuciance, though cyclists criticise back that motorists hog the road, pollute, kill, etc.

Hey bro, want to see a movie this Friday at 5?

No man, I'm going to the Critical Mass to challenge the social norm of owning a car! Me and a few hundred other bike riders are going to be celebrating peaceful transportation. You should come. Everyone should come! No Critical mass? Start one!

A large gathering of mostly douchebag hipsters that ride their bikes around the city on the last Friday of the month. Participants feel that since they ride bicycles, they are somehow superior and permitted to break traffic laws.

Did you count the number of hipster douchebags at critical mass? It's over 9000!

Another far left wing terminology to support diversity. Another name for a racial quota.

"Critical mass" means that it is important for a sufficient number of "minorities" to be enrolled on campus so that they not feel "isolated." When the number of blacks dropped at UC Berkeley following the passage of 209, the opponents of 209 argued that the drop in black enrollment created a "hostile environment" for those enrolled. "Critical mass" theory also means that the remainder of the student body needs to see enough black faces so that they can benefit from "diversity."

Don't listen to that hippie fart sniffer, critical mass is just another term for a racial quota.